1. Field of the Invention
The present invention relates to a method for call establishment over a packet exchange network at a high speed according to the procedure conforming to the PPP (Point to Point Protocol).
2. Description of the Related Art
As a transport layer protocol for connecting with the Internet, the TCP (Transmission Control Protocol) has been widely used. When a terminal connects with the Internet via a public network, the PPP (Point to Point Protocol) is generally used. The PPP is also adopted in the third generation mobile phone standard system, cdma2000, for a call establishment in the data communications.
As shown in FIG. 11, in cdma2000, which is the next generation mobile communication system being under standardization in 3GPP2 (3rd Generation Partnership Project 2), a base station (BS), a BS controller, a PCF (Packet Control Function), PDSN (Packet Data Serving Node), and an AAA (Authentication, Authorization and Accounting) server are connected on the network side, in order to realize IP data communications. A mobile terminal side or a user side is provided with communication equipment including an AT (Access Terminal) and TE (Terminal Equipment).
The BS establishes a radio channel with the AT. The BS controller controls the BS. The PCF controls data communications in between the BS controller and the PDSN. The PDSN connects a radio access network with an IP network, and terminates the logical link. A PPP connection is a data transmission path established between the TE and the PDSN. An R-P connection is a data communication path which is established between the PCF and the PDSN when the PPP connection is established. The R-P connection is established for each PPP connection and is assigned with a unique identifier.
FIG. 18 is a chart showing the sequence when the CHAP (Challenge Handshake Authentication Protocol) is adopted for authentication in a Simple IP (SIP) call defined in cdma2000. The CHAP is a security function supported on line. In order to protect against unauthorized accessing, PPP encapsulation is used.
Step (a): A radio channel is established between the AT and the radio access network.
Step (b): An individual R-P connection is established between the PCF and the PDSN.
Step (c): The TE requests the PDSN for CHAP authentication.
Step (d): The PDSN requests the TE for the CHAP authentication, and transmits the maximum packet size MRU receivable by the PDSN. Thereby, a radio channel is established between the AT and the radio access network.
Step (e): The CHAP authentication is accepted by the PDSN.
Step (f): The CHAP authentication and the MRU of the PDSN are accepted by the TE.
Step (g): A challenge message for the CHAP authentication is sent from the PDSN to the TE.
Step (h): A challenge response is generated by the TE, and is sent to the PDSN together with a username.
Step (i): The username, the CHAP challenge and the CHAP response are sent from the PDSN to the AAA server by using an authentication protocol.
Step (j): The authentication result (success or failure) and an IP address “y” used by the TE if needed are sent from the AAA server to the PDSN by using the authentication protocol.
Step (k): The authentication result is sent from the PDSN to the TE.
Step (l): When the authentication has been successful, the PDSN requests the TE to use “x” as an IP address of itself.
Step (m): The TE, to which no address has been assigned, requests the PDSN to use “0.0.0.0” as an IP address of itself.
Step (n): The PDSN requests the TE to use the IP address “y”.
Step (o): The TE accepts that the PDSN uses “x” as its IP address.
Step (p): The TE requests the PDSN to use “y” as the IP address of itself.
Step (q): The PDSN accepts that the TE uses the IP address “y”.
Then, if the TE requests for a DNS server address or the like, an appropriate response is performed.
Step (r): The PDSN requests an authentication server to start charging.
Step (s): The authentication server accepts to start charging.
FIG. 19 is a chart showing the sequence in a case where the PAP (Password Authentication Protocol) is adopted for authentication in the Simple IP (SIP) call. The PAP is an authentication protocol used in a PPP connection, in which information such as a password or the like is sent in a plane text (not encoded), different from the CHAP.
Step (a): A radio channel is established between the AT and the radio access network.
Step (b): An individual R-P connection is established between the PCF and the PDSN.
Step (c): The TE requests the PDSN for PAP authentication.
Step (d): The PDSN requests the TE for the PAP authentication, and transmits the maximum packet size MRU receivable by the PDSN. Thereby, a radio channel is established between the AT and the radio access network.
Step (e): The PAP authentication is accepted by the PDSN.
Step (f): The TE requests the PDSN for PAP authentication.
Step (g): The PDSN requests the TE for PAP authentication.
Step (h): The PAP authentication is accepted by the TE.
Step (i): A username and password are sent from the TE to the PDSN.
Step (j): The username and password are sent from the PDSN to the AAA server by using an authentication protocol.
Step (k): The authentication result (success or failure) and an IP address “y” used by the TE if needed are sent from the AAA server to the PDSN by using the authentication protocol.
Step (l): The authentication result is sent from the PDSN to the TE.
Step (m): When the authentication has been successful, the PDSN requests the TE to use “x” as an IP address of itself.
Step (n): The TE, to which no address has been assigned, requests the PDSN to use “0.0.0.0” as an IP address of itself.
Step (o): The PDSN requests the TE to use the IP address “y”.
Step (p): The TE accepts that the PDSN uses “x” as its IP address.
Step (q): The TE requests the PDSN to use “y” as the IP address of itself.
Step (r): The PDSN accepts that the TE uses the IP address “y”.
Then, if the TE requests for a DNS server address or the like, an appropriate response is performed.
Step (s): The PDSN requests an authentication server to start charging.
Step (t): The authentication server accepts to start charging.
The aforementioned sequences are described in the following non-patent documents:
Simpson, “The Point to Point Protocol (PPP)”, RFC 1661, July 1994;
P.R0001, “Wireless IP Network Architecture based on IETF Protocols”, 3GPP2, July 2000;
P.S0001-A Version 3.0.0, “Wireless IP Network Standard”, 3GPP2, July 2001;
Simpson, “PPP Challenge Handshake Authentication Protocol (CHAP)”, RFC 1994, August 1996; and
A.S0007-0 version 1.0, “1xEV-DO Inter-Operability Specification (IOS) for CDMA 2000 Access Network Interfaces”, 3GPP2, July 2001.
The PPP is a protocol defined for a dial-up connection using a modem, which contains parameters and sequences not used in cdma2000. Thus, it is inefficient if the PPP is used as it is for a call establishment in data communications over a packet exchange network.
For example, in the sequence of using CHAP authentication in the SIP call (FIG. 18), request/reply messages for authenticating the PDSN by the TE are exchanged in Steps (c) and (e). However, these are not performed actually, so they are redundant. Further, in Step (m), the TE sends the IP address (0.0.0.0), and then in Step (n), the PDSN sends the address that the TE should be used. In fact, IP address is always given by the PDSN, whereby the sequence of Step (m) is redundant.
Further, since an uplink speed is low in cdma2000 1X EV-DO, the amount of information must be reduced as much as possible. However, in the PPP, symmetrical sequences are performed in both uplink and downlink, causing low efficiency.